1. Field Of The Invention
This invention is directed to apparatuses for imparting rotation to tubular members and in one aspect to power tongs for making and breaking joints between casing, pipe, and tubing.
2. Description Of Related Art
Tongs are used in the drilling industry for gripping and rotating pipes. Generally, the pipes are gripped between one or more passive jaws and one or more active jaws which can be urged against the pipe. Normally, the radial position of the passive jaws or jaws is fixed and consequently these jaws and/or their jaw holders must be changed to accommodate pipes of different diameters. This necessitates the inventory of different parts and requires a certain amount of time for exchanging jaws and related apparatuses to accommodate tubulars of different diameter.
Various prior art tongs have passive jaws that are fixed with respect to the tong. Accommodation of pipe of varying diameter is accomplished with means other than the fixed passive jaw or jaws.